Annotation of sys/uvm/uvm_io.c, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: uvm_io.c,v 1.16 2005/11/04 21:48:07 miod Exp $ */
2: /* $NetBSD: uvm_io.c,v 1.12 2000/06/27 17:29:23 mrg Exp $ */
3:
4: /*
5: *
6: * Copyright (c) 1997 Charles D. Cranor and Washington University.
7: * All rights reserved.
8: *
9: * Redistribution and use in source and binary forms, with or without
10: * modification, are permitted provided that the following conditions
11: * are met:
12: * 1. Redistributions of source code must retain the above copyright
13: * notice, this list of conditions and the following disclaimer.
14: * 2. Redistributions in binary form must reproduce the above copyright
15: * notice, this list of conditions and the following disclaimer in the
16: * documentation and/or other materials provided with the distribution.
17: * 3. All advertising materials mentioning features or use of this software
18: * must display the following acknowledgement:
19: * This product includes software developed by Charles D. Cranor and
20: * Washington University.
21: * 4. The name of the author may not be used to endorse or promote products
22: * derived from this software without specific prior written permission.
23: *
24: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
25: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
28: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
29: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
30: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
31: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
33: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34: *
35: * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
36: */
37:
38: /*
39: * uvm_io.c: uvm i/o ops
40: */
41:
42: #include <sys/param.h>
43: #include <sys/systm.h>
44: #include <sys/mman.h>
45: #include <sys/proc.h>
46: #include <sys/malloc.h>
47: #include <sys/uio.h>
48:
49: #include <uvm/uvm.h>
50:
51: /*
52: * functions
53: */
54:
55: /*
56: * uvm_io: perform I/O on a map
57: *
58: * => caller must have a reference to "map" so that it doesn't go away
59: * while we are working.
60: */
61:
62: int
63: uvm_io(vm_map_t map, struct uio *uio, int flags)
64: {
65: vaddr_t baseva, endva, pageoffset, kva;
66: vsize_t chunksz, togo, sz;
67: vm_map_entry_t dead_entries;
68: int error, extractflags;
69:
70: /*
71: * step 0: sanity checks and set up for copy loop. start with a
72: * large chunk size. if we have trouble finding vm space we will
73: * reduce it.
74: */
75:
76: if (uio->uio_resid == 0)
77: return(0);
78: togo = uio->uio_resid;
79:
80: baseva = (vaddr_t) uio->uio_offset;
81: endva = baseva + (togo - 1);
82:
83: if (endva < baseva) /* wrap around? */
84: return(EIO);
85:
86: if (baseva >= VM_MAXUSER_ADDRESS)
87: return(0);
88: if (endva >= VM_MAXUSER_ADDRESS)
89: /* EOF truncate */
90: togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
91: pageoffset = baseva & PAGE_MASK;
92: baseva = trunc_page(baseva);
93: chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
94: error = 0;
95:
96: extractflags = UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG;
97: if (flags & UVM_IO_FIXPROT)
98: extractflags |= UVM_EXTRACT_FIXPROT;
99:
100: /*
101: * step 1: main loop... while we've got data to move
102: */
103:
104: for (/*null*/; togo > 0 ; pageoffset = 0) {
105:
106: /*
107: * step 2: extract mappings from the map into kernel_map
108: */
109:
110: error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
111: extractflags);
112: if (error) {
113:
114: /* retry with a smaller chunk... */
115: if (error == ENOMEM && chunksz > PAGE_SIZE) {
116: chunksz = trunc_page(chunksz / 2);
117: if (chunksz < PAGE_SIZE)
118: chunksz = PAGE_SIZE;
119: continue;
120: }
121:
122: break;
123: }
124:
125: /*
126: * step 3: move a chunk of data
127: */
128:
129: sz = chunksz - pageoffset;
130: if (sz > togo)
131: sz = togo;
132: error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
133: togo -= sz;
134: baseva += chunksz;
135:
136:
137: /*
138: * step 4: unmap the area of kernel memory
139: */
140:
141: vm_map_lock(kernel_map);
142: uvm_unmap_remove(kernel_map, kva, kva+chunksz,
143: &dead_entries, NULL);
144: vm_map_unlock(kernel_map);
145:
146: if (dead_entries != NULL)
147: uvm_unmap_detach(dead_entries, AMAP_REFALL);
148:
149: /*
150: * We defer checking the error return from uiomove until
151: * here so that we won't leak memory.
152: */
153: if (error)
154: break;
155: }
156:
157: /*
158: * done
159: */
160:
161: return (error);
162: }
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